In the prior art, for example from EP 1 064 472 B1 and EP 0 598 290 B1 of the applicant, brake levers and slack adjusters, respectively, are known which have proven to be applicable in practical service. Such brake levers comprise a lever section for connection with a brake cylinder and a housing section for attachment to a splined S-cam shaft which controls both brake linings in the drum. An adjustment device is received by the housing section of the brake lever, which comprises a first clutch, the first clutch being biased by a first spring element with a spring force, and a second clutch, the second clutch being biased by a second spring element with a spring force, as well.
Generally, the second clutch is configured as a one-way clutch and comprises a gear tooth forming with a defined number of teeth.
Although the adjustment accuracy of the automatic slack adjusters according to the prior art could have been further improved in that the adjustment steps of the one-way clutch in the adjustment device have been made smaller, see e.g. WO 2011/016047 A1, or in that even a completely step-less one-way clutch has been employed, by which rather highest requirements on safety and reliability of such systems have been met, however, still there exists the need to further increase the accuracy and repeatability of the adjustment movements, in particular with respect to coming requirements in electronic brake monitoring systems.
In this connection it shall peculiarly better be distinguished between a normal functioning and a malfunction of the entire brake system, and the monitoring and warning function of such brake control mechanisms shall be further increased.
One-way clutches, which do perform very small steps or even function continuously, as described e.g. in WO 2011/016047 A1, do clearly show disadvantages with respect to their strengths, i.e. also with respect to the magnitude of the possible force transmission. Furthermore, their wear resistance as well as their resistance against impurities in the lubricating grease is clearly reduced. Such disadvantages shall be avoided.